How to Talk Dolphin
Humans have their difficulty communicating with each other in the same language. Using a different language multiplies the difficulties ten fold. Now dolphins have their own way of communicating and, at times, seem to vaguely understand humans. The scientific community had thought that whistles were the main sounds made by these mammals, and were unaware of the importance and use of burst pulsed sounds. Researchers from the Bottlenose Dolphin Research Institute (BDRI), based in Sardinia (Italy) have now shown that these sounds are vital to the animals' social life and mirror their behavior.
Dolphins have been previously known to emit two distinct kinds of acoustic signals, which are called whistles and clicks.
* Clicks - quick broadband burst pulses which are used for echolocation, although some lower-frequency broadband vocalizations may serve a non-echolocative purpose such as communication.
* Whistles - narrow band frequency modulated signals which seem to be used for communicative purposes such as the signature whistle of bottlenose dolphins.
There is strong evidence that some specific whistles, called signature whistles, are used by dolphins to identify and/or call each other; dolphins have been observed emitting both other specimens' signature whistles, and their own. A unique signature whistle develops quite early in a dolphin's life, and it appears to be created in an imitation of the signature whistle of the dolphin's mother.
"Burst-pulsed sounds are used in the life of bottlenose dolphins to socialize and maintain their position in the social hierarchy in order to prevent physical conflict, and this also represents a significant energy saving," Bruno Díaz, lead author of the new study.
The study, published by the publishing house Nova Science Publishers in the book Dolphins: Anatomy, Behavior and Threats, presents the most complete repertoire ever of these burst pulsed sounds and whistles, gathered using bioacoustics since 2005 in the waters off Sardinia (Italy).
According to the researchers, the whistle sounds allow dolphins to stay in contact with each other (above all mothers and offspring), and to coordinate hunting strategies. The burst pulsed sounds (which are more complex and varied than the whistles) are used "to avoid physical aggression in situations of high excitement, such as when they are competing for the same piece of food, for example," explains Díaz.
The dolphins emit these strident sounds when in the presence of other individuals moving towards the same prey. The "least dominant" one soon moves away in order to avoid confrontation. "The surprising thing about these sounds is that they have a high level of uni-directionality, unlike human sounds. One dolphin can send a sound to another that it sees as a competitor, and this one clearly knows it is being addressed," explains the Spanish scientist.
Whether whistles or burst pulses, this is not the same as what humans understand as language. Evidence exists that these sounds are used for identification and now for establishing a hierarchy of approach.
For further information: http://www.plataformasinc.es/index.php/esl/Noticias/Los-delfines-dialogan-con-diplomacia (Spanish) or http://www.sciencedaily.com/releases/2010/06/100609094355.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29&utm_content=Google+Reader